New changelog entries:
* casper-md5check/casper-md5check.c: Modernize to make sure we can properly
ready md5sums and check integrity of files on images. (LP: #1824672)
* scripts/casper-bottom/01integrity_check: run casper-md5check on tty1.

New changelog entries:
* bin/casper-a11y-enable, scripts/casper-bottom/30accessibility,
ubiquity-hooks/30accessibility,:
- revert the code handling the a11y profiles to its pre-xenial version,
the new a11y-profile-manager component which handled that in xenial
had been deprecated and is not installed since bionic.

New changelog entries:
* Support multi-layered fsimage:
Add a layerfs-path kernel parameter pointing at the leaf to the leaf
layer of an overlay-compatible multi-layer live filesystem
on the medium.
By default, it is not set and multi layer is disabled and falls back
to the default behaviour of casper.
A relative path uses "live-mediate-path" as root directory. All the
layer images of the same hierarchy must be in the same directory.
Manpage is updated.
Co-work with Jean-Baptiste.

New changelog entries:
[ Steve Langasek ]
* debian/casper.service: order this after plymouth on shutdown, so that if
plymouth is present we are reliably talking to it, rather than possibly
racing by writing to console and then having plymouth start behind our
back. LP: #1795882.